The 101>> Race Car Set-up Basics Pt1

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Hours are spent between engineers and drivers describing how a racing car feels in pursuit of that perfect set-up, often accompanied by the universal driver language of hand gestures. The most effective wing in the world isn't going to help you if it's at the wrong angle, or if your camber is out by a fraction and the car is eating its tyres. Winning or losing can be predefined by mere millimetres of difference in the configuration of each aspect of a racing car; every part must work in harmony to obtain the maximum performance.

When I was younger, I used to enjoy spending hours setting cars up on the race sims that were available at the time – perhaps mostly because you could get as much enjoyment from that as from the relatively simplistic, blocky graphics available at the time…

Wing angle, bump stops, spring rates; I spent hours tweaking the numbers – and then usually just minutes testing each adjustment out on the virtual track (mostly in a desperate attempt to beat my uncle, who was the IndyCar Racing king). And I think that at the time I actually had an idea of what all those things meant, the reaction to each action. I can't say I do any more, unfortunately.

With modern games looking so great, it's easy to play a game just to be blown away by the look of the cars rather than how well they drive. You can let practice and the science of set-up disappear; why not just set it to rookie mode, use other cars as your brakes and the barriers to help you round corners?

In real life there isn't that luxury. Race weekends are short and track-time limited. Most importantly, car parts are expensive and drivers fragile, as we've unfortunately found out far too often recently. Whatever performance a driver is able deliver out on track, their efforts are made or unmade by the way the car has been set-up. You want to win? You need to have the car underneath you to do it. So how do teams go about setting up a car for a race? What do all the terms mean, and what real-life effects do they have? Luckily I have Speedhunters' own tame racing driver, Edward Sandstrom, to help explain.

So what are the main areas of focus for setting up a race car? Let's start with the definitions of terms and what's available, using Edward's FIA GT3-spec BMW Z4 as an example. GT3 cars are heavily stripped-out road cars: there are many limitations on what you can and can't change, and no in-season development is allowed. The FIA carry out performance balancing at the beginning of a season to ensure that the potential of each GT3 model is as equal as possible – this is then constantly reviewed during the year. This means that only way to maximise the driver's potential is to fine-tune the set-up of the car.

DOWNFORCE

The most visible sign of a car's set-up is its aero package. GT3 cars have big rear wings, which are balanced with the front splitter and, if necessary, dive planes. Edward, how do you decide on a downforce level for a race weekend?

Edward: BMW provide us with general information regarding different downforce levels on the car. But of course we do analyse the track beforehand to get the right amount of downforce or at least set up a test program to find a baseline. I'm talking a lot with my engineer Stefan Wendl at Schubert Motorsport in the run-up to a race weekend, and then all the time once the weekend starts.

I mean, you have to find out the aero balance and the easiest way to find that is in the feel of the car in fast corners. You want to make the aero so efficient that it doesn't change too much between front and rear in different speeds. We can change the upper and lower rear wing angle to adjust the balance between front and rear. We also have the diffuser that you can affect by different rake angles of the car. But we aren't allowed to do much more than that in FIA GT3.

ENGINE RESTRICTORS

There is a wide variety of engines being used in GT3, from the howling front-mounted 6-litre V12 of the Aston Martin DBRS9 to the 4-litre, rear-engined 6-cylinder Boxer on the Porsche 911. In an effort to keep the GT3 speeds reasonable (and not to embarrass their GT2 and even GT1 cousins, which they could potentially keep up with out on track given full freedom) the engine power is held back by the use of air restrictors: these reduce the flow of air through the engine intakes and therefore reduce the power.

In GT3 each manufacturer's engine power is set at the beginning of the year during Balance Of Performance testing, and then altered as necessary depending on results. Edward, how much effect do the restrictors have? What can you do to counter-act being handed smaller restrictors, if anything?

Edward: I can't do anything… Less air means less horsepower, so what can you say? But an engine with more torque won't be affected as much as an engine with less. Every engine supplier of course finds their way to adapt things a bit for a smaller restrictor, but you never walk away from it with the same amount of HP. I think it's important to have a camshaft with a wider range when you get a restrictor. You can also change the engine mapping to try and claw back performance.

GEARING

In an ideal world where money was no object, gear ratios would be changed to suit each difference track's characteristics: you're always looking to top out your speed on the longest straight at any track. Edward, can you change ratios in GT3? How many gearboxes are you allowed in the season?

Edward: The gearbox is homologated from the start of the year. We are allowed to change the unit as many times as we want, but that's an expensive thing to do – and thankfully we don't seem to have a big issue with them. The only thing we do is to rebuild them between the races. This year BMW introduced the paddle-shift, which seems to make them last even better.

BRAKES

You've configured the car to will max out down the straights – now how do you stop it for the corners? Edward, how much can you change on brakes, except for the obvious consumables like pads? Can you change manufacturer or compound?

Edward: In FIA GT3 the brake disks have to be steel and the size is for sure homologated. Pads we can change between different suppliers to get different friction performances. That can help in terms of trail braking.

EXHAUST

The Z4 has the most recognisable sound on the FIA GT3 grid, with it's big exhausts making a rasping roar, especially on downshifts. Edward, does the exhaust have much impact on the car's performance?

Edward: It's nothing like Formula 1 with their blown diffusers! I actually don't know why they go all the way back… on the M3 GTE car they exit out on the side. On the Z4 it's only made to maximise engine performance – and to make that great sound perhaps!

SUSPENSION, WHEELS AND TYRES

Springs, dampers, anti-roll bars… These areas are are fraught with complication and trade-offs: going in one direction often compromises other areas of performance. The softer a car's suspension, the better it can deal with bumps and potentially the more grip the car will have, but a stiff car will generally be more responsive, can normally run consistently lower to the ground and therefore generate more downforce, whilst also helping with tyre temperature (by putting more load on them). Which wears them out faster…

You also want to counter pitch under heavy braking, where the nose dives and squirms, and body roll, both of which can unsettle the car and cause the driver to lose confidence or simply not be able to get the car to perform to its maximum.

Edward: I mean this is a huge area to get everything working perfectly and give the car the right balance. This area is also a bit related to what an individual driver needs to be fast. Some drivers wants a loose rear and some don't. In general I think downforce saves tyres: the worst thing is actually too much drift. That generates a lot of heat and also rips off a lot of rubber from the tyre. Tyres are the last thing you have against the ground so you have to analyse them all the time to see what's going on.

To optimise downforce a stable platform in terms of roll-bars and springs helps. But then you want to maintain a good downforce level even at lower speeds. As soon the car starts being bad in lower speed you have to react to create more grip; then you have to analyse if you can find grip through dampers or anything else without affecting the stable platform. If the aero isn't good enough it's maybe better to find more mechanical grip with a softer set-up. Personally I need a really good front end to be able to drive the car fast. Understeering makes me passive and confused of how to drive.

The four circles of rubber that are (hopefully) the only thing in contact with the track are the most critical part of the package, and the most time is spent by teams trying to optimise the tyre performance by altering settings in the wheel wells than any other part of the car.

Wheels are angled out from the perpendicular centre-line of the car (camber adjustment) so the bottom of the tyre sticks out further than the top. This gives the tyres negative camber, which works with the suspension geometry and characteristics of the circuit to maintain the most consistent contact patch possible.

That always seemed counter intuitive to me, but it's about maximising traction as the car heels in a corner. Front wheels in particular can also be angled slightly inward towards each other (the toe-angle) to help with steering and tyre wear.

The rubber itself is the biggest variable: tyres are living things, constantly changing form and feel during a race (usually for the worse as they get over-heated and easier to damage), meaning the driver has to stay on top of the feedback they're giving him. Different manufacturer's products have different characteristics, giving yet another decision to make in GT3, as it's a free-tyre formula. Team NFS swapped from Dunlops to Michelin rubber towards the end of the season.

Edward: Tyres are the black dirty things that cost a lot of money, but when they're working they bring the special moments of being a race driver and having perfect grip in the car. Regarding the difference between Dunlop and Michelin this year, it was due to the different approaches taken by each company. Last season we had a big advantage on the Dunlop after half an hour in the race. In contrast, the Michelin instead had a advantage in qualifying.

Some races last year we experimented a bit too much with the air pressure and therefore got some punctures. It felt like Dunlop made our tyres to last even longer this year, maybe because of that. Michelin also increased their endurance performance for this season, but they somehow could keep their performance in qualifying. In the end the Michelin have had an advantage in the FIA GT3 Championship this year. Instead I think Dunlop would be a better choice in the Blancpain Endurance Series when you have longer stints. We had a really good gain from the Dunlop tyres at this year's Spa 24 Hours for example.

In general setting the camber, toe angles and tyre pressure is a really big part of the race weekend. You need to optimise them to get the most of the tyres and make them last in the best way. Sometimes you have to think out of the box to generate the most out from the tyres. I find it really exciting to analyse the wear of the tyres because you can learn so much from that and may be able to change things to make the car even faster. But it's often a compromise between fast and slow corners and sometimes the amount of left and right corners.

DATA ANALYSIS

Data engineers are now key in understanding how to get the best from a racing car. Working with the drivers and mechanics, they help interpret the driver's performance on track and his explanation of the car's behaviour so the set-up can be altered and improved. Drivers can often been seen huddled around the data stations, picking through the data traces.

Edward: Data engineers have a lot of data to go through to check the cars' performance and to make sure that everything works according to plan. The software they use monitors a huge range of parameters: every measurable aspect of the car. As a driver I concentrate on a specific set of parameters, which makes it easier.

The graphs I need to understand are the throttle, brake, speed, steering angle and gears, and I need to overlay the data between my laps. After a while you learn to see racing lines only from the speed graph and already be able to change your driving if needed. It's a perfect tool to nail small details in your driving, but you need to make sure you don't fall into the data too much – you need to use it in combination with what you've learned out on track.

You can't understate how much racing is a team sport – and how reliant it is on the expertise of everyone involved. In the next part we'll see how all this set-up know-how is applied during a typical race weekend.

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